1. Field of the Invention
The prevent invention relates to a substantially box-shaped air bag case having a bottom wall portion and a side wall portion which rises from an outer circumferential edge of the bottom wall portion into a substantially cylindrical shape and configured not only to accommodate a folded air bag but also to allow the air bag to project from an upper opening portion thereof when the air bag is inflated.
2. Description of the Related Art
Some of conventional air bag cases have a configuration in which in a single metallic sheet material, a side wall configuring portion which configures a side wall portion is bent so as to rise from an outer circumferential edge of a bottom wall configuring portion which configures a bottom wall portion and a plurality of joining piece portions provided on the side wall configuring portion are superposed on corresponding joined portions so that the joining piece portions and the joined portions are crimped together to thereby maintain the rising shape of the side wall portion from the bottom wall portion (refer, for example, to JP-A-2011-57165).
In such a conventional air bag case, however, in the side wall configuring portion, the joining piece portions extend from an edge portion of the side wall configuring portion which lies on a side facing the other adjacent side wall configuring portion towards the other side wall configuring portion and are disposed so as to be substantially at right angles to the bottom wall portion. Namely, in this conventional air bag case, the direction in which the joining piece portions are superposed on the joined portions to be crimped together intersects the direction in which the side wall configuring portion is bent to rise from the bottom wall configuring portion in fabricating the case. Thus, in the fabricating process of the case, the crimping step and the bending step of bending the side wall configuring portion cannot be performed in the same step but have to be performed in separate steps, leaving room for improvement in simplifying the fabricating process of the case.